Method of electrical distribution



(No Model.)

. J. BURKE. H METHOD OF ELEGTRIGAL DISTRIBUTION.

/ No. 554,240. Patented Feb. 11, 1896.

' I l 13 1 J /20 WITNESSES:

"INVENTOR kovwwu MW BY UNITED STATES PATENT OEEIcE.

JAMES BURKILOF SCI-IENECTADY, NET? YORK, ASSIGNOR TO THE THOMSON- IIOUSTON ELECTRIC COMPANY, OF BOSTON, MASSACHUSETTS.

METHOD OF ELECTRICAL DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 554,240, dated February 11, 1896.

A li ation filed December 24, 1894. Renewed January 6, 1896. Serial No.574,561. (N0 model.)

To all whom it may concern/.-

Ke it known that I, JAMES BURKE, a subject of the Queen of Great Britain, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Methods of Electrical Distribution, of which the following is a specification.

The present invention comprises a method and certain novel means for supplying from a single generator or group of generators current of different potentials in two or more electric circuits, or to such portions of a common distribution system. as require a different potential on the feeders at the central station in order to compensate for the different amounts of drop in the feeders, which arise from causes well known to electrical engineers.

In central-distribution systems as now installed it is customary to employ bus-bars, maintained at any desired difference of potential, from which the feeders lead to different portions of the system. In such cases it often occurs that one or a group of feeders require more current than is supplied by the regular generators, so that a reserve machine must be used to supply the emergency. It has been impracticable heretofore to supply current from a single reserve machine or group of machines to more than a single busbar at a time, owing to the different potentials at which the bus-bars are normally maintained.

I have designed the present invention es pecially with a view to meeting this emergency and rendering it possible to divide the current from a single machine, supplying part of the current to one bus-bar or set of feeders at one potential, and the remainder of the current to other bus-bars or feeders at a different potential.

The invention will be described as applied to such a system of distribution, though it will also be found useful in many other connections, as will be understood by electrical engineers.

To illustrate a simple typical embodiment of the invention, assume a two-wire distribution system in which the positive feeders are connected to two bus-bars maintained at diiferent potentials by generators of correspondingly different voltages, or other wellknown means. If, then, it becomes desirable to supply additional current to these bus-bars from a supplementary or reserve machine the machine will be connected to the bus-bars through intermediate variable sources of electromotive force, wherebysubstantially all the current of the reserve machine may be supplied to either bus-bar at the proper potential, or the current may be divided between the two bus-bars at different potentials, corresponding to the normal values maintained thereon. To effect this division of the current I employ, preferably, a pair of CIYlltlllOdllfifllllIlGS, with their armatures connected in series across the bus-bars and running in unison. One terminal of the reserve machine is then connected between the two armatures, while the negative terminal will be connected to the common negative bus-bar. The fields of the regulating-machines are energized with current from any suitable source of supply, and means are provided for regulating the electromotive forces of the machines inversely, so that the potential of the current supplied to one bus-bar.1nay be raised and that supplied to the other bar may be lowered in any desired ratio.

The accompanying drawing shows in diagram a distribution system embodying the invention, such as has just been described.

A B represent the positive bus-bars of a two-Wire distribution system, and C is the common negative bus-bar. I will assume that the standard potential maintained on the bus A is one hundred and forty volts and that on bus Bis one hundred and twenty volts.

G G are the main generators normally supplying current to the respective bus-bars.

G represents an additional or reserve machine which may be used to help out either of the main generators or both of them at the same time. For this purpose its negative terminal is connected to the negative bus C, and its positive terminal is connected to the bus-bars A B through variable sources of electromotive force, comprising two dyname-machinesl l arranged in the following manner.

The armatures f f ot' the machines are coupled in series between the busbars A B, and the generator G is connected to a point between the arinatures, as indicated. field windings c e of the machines may be energized by current derived from any suitable source. For this purpose I have shown them connected .in multiple between the busbar 13 and. the negative bus 0. Resistances R R are included respectively in the holdcircuits (2 c, and a rheostat-arm ll. so arranged as to cut resistance into one circuit simultaneously with cutting it out of the other circuit.

The generators G (1" (l are shown as shuntwonnd and provided with rheostats R .i'or regulation in the ordinary manner. The construction of these machines is, however, in no sense a materialpart of the invention. Feeders I and l are shown leading from the respective bus-bars A 1;. l y open in g the switch r and closing the switch r upon one or the other of contacts 15 t the generator G' may be thrown wholly upon either of the bus-bars when desired.

In a practical installation I should prefer to couple up the generators so that any one of the machines may either be connected to one of the common station bus-bars directly or coupled to both sets of busscs through the machines F 1*". This can be readily accomplished by suitable switches, as an electrical engineer will readily understand. The arm atures of machines F E will be mounted on the l same shaft or so geared as to run in unison.

The operation of the invention will now be described.

It the conditions are such that substantially the total current of the dynamo G is needed upon the bus B, the rhcostat-arm II will be so thrown as to introduce a maximum amount of resistance in the field-circuit c, or preferably to break the circuit altogether. The machine F will then run idle, and except for ohmic losses there will be no di l'ference of potential between its terminals, while, on the other hand,the field strength and counter electroniotive force of machine 1 is at a maxi mum, and the machine will absorb substantially all of the twenty volts normal difference of potential between the bus-bars A 13. The generator G will now be delivering current to the bus 13 at one hundred and twenty volts, it being understood that the machine is so regulated that its voltage is of substantially this value. If the rheostat-arm ll be thrown to the other extreme position the conditions will be reversed. The machine I will then run idle, and there will be practically twenty volts ditlerence of potential between the terminals of the machine F. If the voltage of the generator G is then raised to one hundred and forty it will deliver current to the bus-bar A at the properpotential.

vide the total twenty volts dil't'erence ol poi tential between the two armaturcs ff in the The proper ratio. Assume that it placed in the central position. Then there will be ten volts difference of potential between the terminals ot' each of the armaturesfj, and it the generator G is properly regulated its current will divide equally between the bus-bars A 13, the clcctromotive force in armaturej'" acting to assist or boost up the voltage of the current delivered to bus A to one hundred and :forty volts, and the clectromotive .Iorce in armature f acting to reduce or boost down the electromotive force of the current going to bus I to one hundred and twenty volts. lit a similar manner, well understood, the current: of the generator (1 maybe divided bet ween the b usbars in any desired ratio, and will. be always supplied to the bars at the proper potentials. The invention ol? course may be applied to more extended systems oi. distribution than that herein shown, comprising any number of bus-bars necessary in a given instillation. It is also equally applicable to three-wire distribution systems, in which the only addition required would be to duplicate the arrange ment described on the two sides olf the tem. For example, what is herein illustrated would, in a threeavirc system, be proper lfor one branch of the system between the positive busscs and the neutral bus, and the arrangement would be duplicated between the neutral bus and the negative busscs.

Having thus described my invention, what I claim as new, and desire to secure by'lietters latcnt, is-

1. The combination oi two or more circuits or portions of a distribution system, with means for maintaining thereon dill'erent potentials, sources of clectromotive 'l'orcc con ncctcd between such circuits in series, whose sum is substantially equal to the difference of potential between the circuits, a generator connected at a point between the said sources of electromotive force, and feeding current through them respectively to the said firstnamcd circuits, and means for regulating inversely the values of the said electromotive forces, as set forth.

2. The combination of two or more circuits or portions of a distribution. system, with gen erators maintaining dillicrent potentials in such circuits, a number of dynamo-machines running in unison and coupled in series be tween the different potential circuits, and a source of current-supply connected ata point: between the armatures of said machines and adapted to feed current to the first-mulled circuits at their respective potentials, as described.

The combination of a number of electric circuits or portions of a distribution system, at which different potentials are normally the electromotive force in the other machine, as set forth. 10

In Witness whereof I have hereunto set my hancl this 22d day of December, 1894. 1

JAMES BURKE.

Witnesses:

B. B. HULL, GENEVIEVE HAYNES. 

